El Niño may make 2014 the hottest year on record

HOLD on to your ice lollies. Long-term weather forecasts suggest 2014 will be the hottest year on record, because climate bad boy El Niño seems to be preparing to spew heat into the air.

An El Niño occurs when warm water deep in the Pacific rises to the surface. It brings rain to South America, and drought and fires to Indonesia and Australia. It is part of a cycle called the El Niño-Southern Oscillation.

It is hard to tell before spring if an El Niño will happen in a given year. “The El Niño-Southern Oscillation cycle more or less reboots around April-May-June each year,” says Scott Power of the Bureau of Meteorology in Melbourne, Australia.

Now a model aims to predict El Niño by examining a previously unexplored feature of Pacific weather.

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Armin Bunde of Justus Liebig University in Giessen, Germany, and his colleagues looked at the link between air temperature over the equator and in the rest of the Pacific. Records showed that, in the year before each El Niño, the two regions became more closely linked, so their temperatures became more similar than at other times.

Bunde found that if these links reached a critical strength, around 75 per cent of the time an El Niño formed within a year (PNAS, doi.org/rdn). “There is certainly a correlation between the cooperative mode in the atmosphere that we measure and the onset of an El Niño event,” he says. Nobody knows why.

Now Bunde says the threshold was crossed in September 2013, so there is a 76 per cent chance of an El Niño this year (PNAS, doi.org/rdv).

A threshold was crossed in September 2013, so there is a 76 per cent chance of an El Niño this year

Thanks to climate change, 2014 is likely to be one of the hottest years on record. An El Niño would make it even hotter, maybe the hottest ever, says Wenju Cai of the CSIRO, Australia’s national research agency, in Melbourne. But since El Niño normally straddles two calendar years, it might give 2015 that title.

This article appeared in print under the headline “El Niño may make 2014 the hottest year yet”